It has been known since many years how to achieve cardiac stimulation by means of an electric signal generator which is usually implanted under the thorax skin and connected to the internal wall of the heart by a lead passing through a vein such as the sub-clavian vein. This lead called either a catheter or an endocardiac probe, is formed of an helically wound metal wire enclosed within a flexible sheath, made for instance of silicone rubber, and ending with a conductive piece intended for being brought into contact with the inner wall of the heart muscle, this piece being the actual electrode.
The utilization of novel types of electrodes made of inorganic materials such as pyrolythic carbon or vitreous carbon, etc., or ceramics having zero plasticity and low tenacity requires a flexible and reliable system for connecting the electrode to the lead. This fixation system will, more often than not, provide for both the mechanical link and the electrical link between the electrode and the conductor. It is moreover desirable that the system being selected should lend itself to an easy mounting, using interchangeable standard elements which will make it possible, more particularly, to place electrodes made of different materials and having different shapes and surfaces. It is worthwhile to be enabled to modulate the electrode surface, for instance to reduce this surface, thereby increasing the local current density and leading to a lowering of the stimulation thresholds and of the energy required for stimulating heartbeats.